People who had recently stopped taking cocaine and heroin addicts also had an impaired pathway.
The study involved more than 179,000 schoolchildren in 40 countries.
Scientists analyzed data on 1,229 people over 30 across the US who were tracked for nearly a decade.
Depression, anxiety and even nicotine consumption decreased.
Research indicates that the compound does not enter the brain which means it is far less likely to be addictive and cause side effects.
By Hamish Morrison via SWNS A former Scots Guard who protected the Queen at Buckingham Palace told how he turned his life around after becoming addicted...
"We found that controlled, low doses of ketamine combined with psychological therapy can help people stay off alcohol for longer than placebo."